Fluorescence studies on the interaction between pyrene‐labelled poly(acrylic acid) and cyclodextrins

The interactions, in aqueous media, between a pyrene‐labelled polyelectrolyte poly(acrylic acid) (PAAMePy) with two different degrees of labelling and β‐ and γ‐cyclodextrins (β‐ and γ‐CD) were studied using absorption and fluorescence (steady‐state and time‐resolved) techniques. In addition to qualitative and quantitative parameters obtained from absorption and steady‐state fluorescence spectra, time‐resolved fluorescence data are presented, allowing additional important observations regarding the nature of the interactions. From the overall data it was possible to conclude that in the case of interaction with γ‐CD the efficient encapsulation of two pyrene units into the cavity of the cyclodextrin molecule leads to a decrease in the number of available free monomers and an increase in the number of preformed ground‐state dimers (GSDs) of pyrene. It was also shown that contrary to the situation in water, where only intramolecular interactions are present, the addition of γ‐CD leads to new interpolymeric interactions. The absence of significant changes is noted when the interactions of PAAMePy polymers take place with β‐CD. The excimer‐to‐monomer fluorescence intensity ratio (I_E/I_M) was found to increase with the added amount of γ‐CD but not with β‐CD. This increase is justified on the basis of the increase of the GSD contribution. The photophysical behaviour was found to be dependent on the pH of the media, but with the absence of relevant interactions between CD and PAAMePy polymer at alkaline values. Copyright © 2007 Society of Chemical Industry     

Stability and performance analysis of randomly deployed wireless networks

A growing demand for mobile services is taking the deployment of wireless local area networks away from the notion of carefully planned and carefully managed settings into randomly deployed and independently managed (if at all) network settings. This results in contentious networks that serve highly mobile nodes. In fact, research reveals that in most metropolitan cities in Europe and the US the size of closely located and contentious access points is overwhelmingly high (in the order of thousands). Subsequently, the performance of these networks is often unstable and unpredictable. This paper aims to investigate the extent of performance fluctuations in randomly deployed networks. It also aims to investigate the contribution of various adaptation strategies at different abstraction layers to deal with these fluctuations. We present the outcome of an exhaustive simulation for different applications, including VoIP, HTTP, and FTP. We will demonstrate that collision due to hidden-terminals is a minor influence on the performance and stability of these networks, whereas dynamic channel allocation greatly affects them. Moreover, HTTP applications are less affected by both inter- and intra-channel interferences compared with FTP and VoIP applications.     

Middleware Support for Transparent Client-Side Caching

This paper reflects on existing caching concepts in proxies and stubs of component technologies and lines out their advantages and deficiencies. A new concept is introduced that averts proliferation of component stubs on client side while transparently providing efficient caching of attributes that doesn't require any changes to existing code at all. Common object-oriented design facilities and code generation tools are leveraged to support seamless integration of these caching concepts into the development cycle.     

Standardized code quality benchmarking for improving software maintainability

We provide an overview of the approach developed by the Software Improvement Group for code analysis and quality consulting focused on software maintainability. The approach uses a standardized measurement model based on the ISO/IEC 9126 definition of maintainability and source code metrics. Procedural standardization in evaluation projects further enhances the comparability of results. Individual assessments are stored in a repository that allows any system at hand to be compared to the industry-wide state of the art in code quality and maintainability. When a minimum level of software maintainability is reached, the certification body of TüV Informationstechnik GmbH issues a Trusted Product Maintainability certificate for the software product.     

Selective capacity of glass-wool filtration for the separation of human spermatozoa with condensed chromatin: a possible therapeutic modality for male-factor cases?

PURPOSE: The aim of this study was to evaluate chromatin condensation of human spermatozoa following swim-up compared to glass-wool separation. Semen aliquots from men attending an andrological outpatient clinic were processed by means of a swim-up procedure and glass-wool filtration. Chromatin condensation was recorded using aniline blue staining and results were reported according to color intensity of stained sperm heads. Morphometric measurements of sperm heads were performed on stained sperm samples. RESULTS: Glass-wool filtration resulted (i) in a significantly higher total motile sperm count (P < 0.0005) compared to swim-up and (ii) in a significantly higher percentage of normal chromatin-condensed spermatozoa compared to the ejaculate (P < 0.01). CONCLUSION: In contrast, comparing swim-up to the ejaculate, the percentage of matured nuclei (unstained spermatozoa) retrieved following swim-up was significantly lower (P < 0.005). Glass-wool filtration separates human spermatozoa according to motility and size of the sperm head. The size of the sperm head closely correlated with the chromatin condensation quality.     

Studies on biotechnical ovulation synchronization in young cows. 1. Ovulation periods, ovarian findings and fertilization results after use of Metallibur, 750 IE PMS and 250 or 500 IE HCG

The following treatment was applied to 50 mature young sows in two experiments (22 and 28 animals) throughout 20 days: Turisynchron-Pr?mix (Turi.), 5 g/animal, and 750 IU PMS (Prolosan serum) 28 hours after Turi. In the first experiment. 250 IU HCG (Gonabion) were additionally injected to each of twelve animals 100 hours after Turi., while in the second experiment each of ten animals recieved 500 IU HCG 103 hours after Turi. The remaining animals of the two groups were used as controls. Inseminations took place 101 and 104 hours (fourth day) after Turi. in the first experiment and 125, 149, as well as 173 hours (fifth, sixth, and seventh days) after Turi. in the second. Onset of ovulation was brought forward to the sixth day after Turi. in response to 500 IU HCG by laparotomy performed in the mornings and evenings of the fourth through seventh days. Most of the controls and test animals with 250 IU HCG ovulated on the sixth or seventh day after Turi. Ovulation was stimulated by both HCG dosages, in comparison to the controls, which was established by slaughtering the animals between the seventh and twelfth days after Turi. The percentage of ovulations was higher among the test animals and that of ovarian cysts lower. Fertilisation of the second group was clearly better than that in the first where insemination had taken place two days prior to ovulation, that is too early. The latter results were secured by tubal douche and ovocyte tests.     

Damped second-order Rayleigh-Timoshenko semi-infinite beam vibration—an exact complex dynamic member stiffness matrix

A uniform linear semi-infinite beam in a uniform linear ambient medium is studied. The beam performs stationary harmonic damped non-synchronous space vibration in simultaneous tension, torsion, bending and shear. Hysteretic and viscous dampings of the beam material and ambient medium are considered. Four new generalized complex Kolousek functions are derived. A 6 × 6 complex symmetric stiffness matrix is established for a semi-infinite beam member excited at its end by prescribed harmonic translations and rotations which have the same frequency but may be out of phase. This matrix extends the range of application of the so called ‘exact analysis’ of non-proportionally damped built-up beam structures as described in a previous paper by Lundén and Åkesson.¹ Numerical examples are given, including applications of the computer program SFVIBAT-DAMP. Power flows are studied.     

Self-defeating personality, depression, and pleasure from activities

Prior research has shown people who scored high on a measure of self-defeating personality experienced less pleasure from various activities and accomplishments. The present research replicated the initial study with 55 men and 60 women, while controlling for the effects of depression. Analyses indicated that, while depression and self-defeating personality were related, depression was not the entire answer for why people with self-defeating personality derive less pleasure from activities.